Inflammatory bowel disease (IBD), which occurs world-wide and afflicts millions of people, is the collective term used to describe three gastrointestinal disorders of unknown etiology: Crohn's disease (CD), ulcerative colitis (UC), and indeterminate colitis (IC). IBD, together with irritable bowel syndrome (IBS), will affect one-half of all Americans during their lifetime, at a cost of greater than $2.6 billion dollars for IBD and greater than $8 billion dollars for IBS. A primary determinant of these high medical costs is the difficulty of diagnosing digestive diseases and how these diseases will progress. The cost of IBD and IBS is compounded by lost productivity, with people suffering from these disorders missing at least 8 more days of work annually than the national average.
Inflammatory bowel disease has many symptoms in common with irritable bowel syndrome, including abdominal pain, chronic diarrhea, weight loss, and cramping, making definitive diagnosis extremely difficult. Of the 5 million people suspected of suffering from IBD in the United States, only 1 million are diagnosed as having IBD. The difficulty in differentially diagnosing IBD and determining its outcome hampers early and effective treatment of these diseases. Thus, there is a need for rapid and sensitive testing methods for prognosticating the severity of IBD.
Although progress has been made in precisely diagnosing clinical subtypes of IBD, current methods for determining its prognosis are non-existent. Thus, there is a need for improved methods for prognosing an individual who has been diagnosed with IBD, the severity of the disease, and whether the individual will respond to therapy. Since 70% of CD patients will ultimately need a GI surgical operation, the ability to predict those patients who will need surgery in the future is important. The present invention satisfies these needs and provides related advantages as well.